Problem motion capture Blender
To me you will only need to Bones, one connecting the ankle with the heel and another connecting the heel with the toes.

First you need to construct the armature properly:


Shift+A add armature, then add a bone
Select the two markers 01, 04 to position in between, and align 3D cursor with Shift+S then Cursor to Selected, this will position the bone between the two markers.
Then enter edit-mode of armature and select the bone and Shift+S then Selection to Cursor
Select the markers 05, and align 3D cursor with Shift+S then Cursor to Selected
Then enter edit-mode of armature and select the second bone and Shift+S then Selection to Cursor


The second step is adding bone constraints:


For the first (root) bone use two Copy Location constraint with second on 50% influence to get in between position of two markers 01 and 04. Then add Damped Track to track marker 05
For the second bone use two Damped Track constraints with second on 50% influence to get in between position of two markers 02 and 03.


Result is shown as below:



The updated .blend file can be found here: